Battery and battery housing

ABSTRACT

A battery including an electrode assembly having electrode plates, a can defining a space receiving the electrode assembly, and a cap plate covering the space, wherein the cap plate is configured to deform away from the space when predetermined sides of the can are deformed toward the space.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation application based on pending application Ser. No.11/373,209, filed Mar. 13, 2006, the entire contents of which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a battery. More particularly, thepresent invention relates to a battery and battery housing configured toaccommodate externally-applied pressure in a safe manner, wherein a capportion can be bent in a predetermined direction when the battery issubjected to a transversely-applied pressure, in order to increase amargin of safety against potential short circuits.

2. Description of the Related Art

It is common for portable devices, e.g., video cameras, portable phones,laptop computers, PDA's, and other light weight multi-function devicesto employ batteries, including secondary batteries, as a source ofelectric power. Types of secondary batteries include, e.g., nickelcadmium batteries, nickel hydrogen batteries, nickel zinc batteries,lithium secondary batteries, etc. The lithium secondary battery, inparticular, is commonly employed due to its rechargeability, largecapacity and compact size. The lithium secondary battery also exhibits ahigh operational voltage and a high energy density per unit weight,making it increasingly popular for the latest portable electronicdevices.

FIG. 1 illustrates an exploded perspective view of a conventionalbattery. Referring to FIG. 1, a conventional battery may include anelectrode assembly 112 having a positive electrode plate 113, a negativeelectrode plate 115 and a separator 114. The battery may further includea housing to enclose the electrode assembly 112, the housing including acan 110 for receiving the electrode assembly 112 and an electrolyte, anda cap assembly 120 for tightly sealing an upper opening 110 a of the can110.

The electrode assembly 112 may have the separator 114 wound between thepositive electrode plate 113 and the negative electrode plate 115. Apositive electrode tap 116 may be coupled to the positive electrodeplate 113 and may protrude from an upper end of the electrode assembly112. A negative electrode tap 117 may be coupled to the negativeelectrode plate 115 and may protrude from the upper end of the electrodeassembly 112. The positive electrode tap 116 and the negative electrodetap 117 may be spaced apart by a predetermined distance and may beelectrically insulated from each other. The positive electrode tap 116and the negative electrode tap 117 may be made of metal, e.g., nickel.

The can 110 may be made of, e.g., aluminum or an alloy thereof, and maybe formed by, e.g., a deep drawing method. The can 110 may have asubstantially flat bottom surface.

The cap assembly 120 may include a cap plate 140, an insulation plate150, a terminal plate 160 and an electrode terminal 130. The capassembly 120 may be associated with a separate insulation case 170, andmay then be coupled to the upper opening 110 a of the can 110 so as totightly seal the can 110.

The cap plate 140 may be made from, e.g., a metal plate, and may have asize and shape corresponding to those of the upper opening 110 a of thecan 110. The cap plate 140 may have a hole 141 formed therethrough at acenter portion thereof. The hole 141 may have a predetermined size forreceiving the electrode terminal 130.

The cap plate 140 may also have an electrolyte injection hole 142 formedtherein in a suitable location, e.g., offset to one side. Theelectrolyte injection hole 142 may have a predetermined size and may besealed by a sealing means 143. The electrolyte injection hole 142provides for electrolyte to be injected through the cap assembly 120after the cap assembly 120 is coupled to the upper opening 110 a of thecan 110. After injection of the electrolyte, the injection hole 142 maybe sealed.

The insulation plate 150 may be made from an insulation material and maybe attached to the lower surface of the cap plate 140. The insulationplate 150 may have a hole 151 formed therethrough corresponding to thehole 141, such that the electrode terminal 130 may pass through the hole151. The insulation plate 150 may also have a receiving recess 152formed in a lower surface thereof, in order to receive the terminalplate 160.

The terminal plate 160 may be made of a metal, e.g., a nickel alloy, andmay be attached to the lower surface of the insulation plate 150. Theterminal plate 160 may have a hole 161 formed therethrough correspondingto the hole 141, such that the electrode terminal 130 may pass throughthe holes 141, 161. The electrode terminal 130 may make contact with theterminal plate 160, e.g., along a contact region at the periphery of thehole 161. Accordingly, the electrode terminal 130 may pass through theholes 141, 151 and 161 and may be electrically connected with theterminal plate 160 while being electrically insulated from the cap plate140 by a gasket 146 and the insulation plate 150.

The negative electrode tap 117, which is coupled to the negativeelectrode plate 115, may be welded to a side of the terminal plate 160.The positive electrode tap 116, which is coupled to the positiveelectrode plate 113, may be welded to a side of the cap plate 140opposite to the negative electrode tap 117. Alternatively, the negativeelectrode tap 117 may be welded to the cap plate 140, and the positiveelectrode tap 116 may be welded to the terminal plate 160. Suitablewelding methods may include, e.g., resistance welding, laser welding,etc. Of these, resistance welding may be particularly suitable.

The electrode terminal 130 may have the gasket 146 mounted thereon. Thegasket 146 may be made of any suitable insulating material including,e.g., the material used for the insulation plate 150. The gasket 146 maybe any suitable form, including, e.g., tubular, annular, flat with ahole defined therethrough, etc. The electrode terminal 130 may beinserted, along with the gasket 146, into the hole 141, such that theelectrode terminal 130 is insulated from the cap plate 140.

The electrode terminal 130 may be connected to the negative electrodetap 117, and thus to the negative electrode plate 115, or it may beconnected to the positive electrode tap 116, and thus to the positiveelectrode plate 113, so as to operate as a negative or positiveelectrode terminal.

The battery illustrated in FIG. 1 may be a conventional lithiumsecondary battery. Battery designs for the latest portable devices maytake advantage of the lithium secondary battery's high energy density toprovide small form factor batteries, e.g., thin batteries having anelongated, rectangular shape. However, such designs may have weakbattery housings, i.e., the battery may not be able to withstand impactor externally applied pressure. In particular, if the battery issubjected to impact or pressure, the electrode assembly contained in thebattery housing may be deformed due to deformation of the can. This may,in turn, result in internal defects such as an internal electric shortcircuit between the electrode plates. Such defects may have seriousresults, including fires and explosions of the battery.

FIG. 2 illustrates a generalized perspective view of a compressedconventional battery housing. In particular, FIG. 2 illustrates aconventional battery housing that has been compressed by a force Faapplied in a transverse direction, i.e., applied to opposing sides ofthe can 110 in a direction normal to the longitudinal axis b. Referringto FIGS. 1 and 2, when the battery is deformed by thistransversely-applied force Fa, as is done during compression safetytests, the substantially flat bottom surface of the can 110 may deforminward and upward. Similarly, the substantially flat top surface of thecap assembly 120 may deform inward and downward.

The deformation or caving-in of the can 110 bottom may apply pressure tothe electrode assembly 112 contained in the battery housing. Inparticular, it may force the electrode assembly 112 upward and againstthe cap assembly 120. This may result in the upper portion of theelectrode assembly 112 coming into contact with various elements of thecap assembly 120, possibly causing an internal electric short circuitbetween the electrode plates and subsequent fire or explosion of thebattery.

SUMMARY OF THE INVENTION

The present invention is therefore directed to a battery and batteryhousing, which substantially overcome one or more of the problems due tothe limitations and disadvantages of the related art.

It is therefore a feature of an embodiment of the present invention toprovide a battery and battery housing configured to accommodateexternally-applied pressure in a safe manner, wherein a cap portion canbe bent in a predetermined direction when the battery is subjected to atransversely-applied pressure.

It is therefore another feature of an embodiment of the presentinvention to provide a battery and battery housing having a concavefeature formed in a lower surface of the cap portion, in order to causethe cap to bend away from the interior of the battery when the batteryis subjected to a transversely-applied pressure.

At least one of the above and other features and advantages of thepresent invention may be realized by providing a battery including anelectrode assembly having electrode plates, a can defining a spacereceiving the electrode assembly, and a cap plate covering the space,wherein the cap plate is configured to deform away from the space whenpredetermined sides of the can are deformed toward the space.

The cap plate may have a protuberance formed upward at a center portionof the cap plate, the protuberance including a stepped portion. Thestepped portion may have a side surface inclined at an angle withrespect to a major surface of the cap plate. The stepped portion mayhave a side surface normal to a major surface of the cap plate. Thestepped portion may have a curved side surface. The stepped portion mayhave a height equal to at least 50% of a thickness of the cap plate. Theprotuberance may have a long dimension with a length of about 20% toabout 70% of the cap plate. The cap plate may include two steppedportions extending away from the space, the stepped portions defining acenter region of the cap plate, a hole may be defined through the capplate in the center region, and the electrode assembly may furtherinclude an electrode terminal disposed through the hole and electricallycoupled to an electrode plate.

The cap plate may have a recess defined in a surface that faces thespace, and end regions of the cap plate may be coplanar with a centerregion of the cap plate. The recess may form a loop in the surface, theloop enclosing the center region. The loop may enclose a substantiallyrectangular region. At least two recesses may be defined in the surface,the recesses extending laterally across a width of the cap plate.

At least one of the above and other features and advantages of thepresent invention may also be realized by providing a battery housingfor a battery electrode assembly, including a body, the body defining aspace to contain the battery electrode assembly, and a cap platedefining an upper wall of the space, wherein an inner surface of the capplate faces the space and includes at least one concave feature. Thebody and the cap plate may be monolithically formed. The concave featuremay be defined by at least one stepped portion, the stepped portionextending away from the space.

The concave feature may be defined by two stepped portions extendingaway from the space and laterally across a width of the cap plate, thetwo stepped portions defining two end regions and a central region, andthe central region may be offset from the two end regions, such that aninner surface of the central region is not coplanar with inner surfacesof the two end regions.

The concave feature may be a groove formed in the inner surface of thecap plate. The groove may be continuously formed in a loop.

At least one of the above and other features and advantages of thepresent invention may further be realized by providing a battery housingfor housing an electrode assembly, including a can having an opening forreceiving the electrode assembly, and a unit for covering the openingwithout short circuiting the electrode assembly if predetermined sidesof the can are deformed inwardly.

The unit for covering may be configured to deform outward, away from theelectrode assembly, if the predetermined sides of the can are deformedinwardly.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent to those of ordinary skill in the art bydescribing in detail exemplary embodiments thereof with reference to theattached drawings in which:

FIG. 1 illustrates an exploded perspective view of a conventionalbattery;

FIG. 2 illustrates a generalized perspective view of a compressedconventional battery housing;

FIG. 3 illustrates an exploded perspective view of a battery and batteryhousing according to the present invention;

FIG. 4A illustrates a plan view of a cap plate for the battery andbattery housing, according to a first embodiment of the presentinvention;

FIG. 4B illustrates a sectional view of the cap plate of FIG. 4A, takenalong line A-A in FIG. 4A;

FIG. 5A illustrates a plan view of a cap plate for the battery andbattery housing, according to a second embodiment of the presentinvention;

FIG. 5B illustrates a sectional view of the cap plate of FIG. 5A, takenalong line B-B in FIG. 5A;

FIG. 6A illustrates a plan view of a cap plate for the battery andbattery housing, according to a third embodiment of the presentinvention;

FIG. 6B illustrates a sectional view of the cap plate of FIG. 6A, takenalong line C-C in FIG. 6A;

FIG. 7A illustrates a plan view of a cap plate for the battery andbattery housing, according to a fourth embodiment of the presentinvention;

FIG. 7B illustrates a sectional view of the cap plate of FIG. 7A, takenalong line D-D in FIG. 7A;

FIG. 8A illustrates a plan view of a cap plate for the battery andbattery housing, according to a fifth embodiment of the presentinvention;

FIG. 8B illustrates a sectional view of the cap plate of FIG. 8A, takenalong line E-E in FIG. 8A; and

FIG. 9 illustrates a generalized perspective view of a compressedbattery housing according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Korean Patent Application No. 2005-0024668, filed on Mar. 24, 2005 inthe Korean Intellectual Property Office, and entitled: “LithiumSecondary Battery,” is incorporated by reference herein in its entirety.

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown. The invention may, however, be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. In thefigures, the dimensions of layers and regions are exaggerated forclarity of illustration. Like reference numerals refer to like elementsthroughout.

A battery and battery housing according to the present invention mayinclude a cap plate configured to prevent internal electric shortcircuits. The cap plate may have a stepped portion formed upward, and acorresponding concave underside, at a central region of the cap plate,such that transverse pressure applied to the battery causes deformationto the cap plate to occur in an upward direction, thereby preventing theupper portion of the electrode assembly contained in the battery housingfrom being pressed against the cap plate and avoiding internal electricshort circuits between the electrode plates.

FIG. 3 illustrates an exploded perspective view of a battery and batteryhousing according to the present invention. Referring to FIG. 3, thebattery according to the present invention may include an electrodeassembly 312 having a positive electrode plate 313, a negative electrodeplate 315 and a separator 314. The battery housing may include a can 310containing the electrode assembly 312 and an electrolyte, and mayinclude a cap assembly 320 for tightly sealing an upper opening 310 a ofthe can 310.

The electrode assembly 312 may have the separator 314 wound between thepositive electrode plate 313 and the negative electrode plate 315. Apositive electrode tap 316 may be coupled to the positive electrodeplate 313 and may protrude from the upper portion of the electrodeassembly 312. A negative electrode tap 317 may be coupled to thenegative electrode plate 315 and may protrude from the upper portion ofthe electrode assembly 312. The positive electrode tap 316 and thenegative electrode tap 317 may be spaced apart and electrically may beinsulated from each other. The positive electrode tap 316 and thenegative electrode tap 317 may be formed from a metal, e.g., nickelmetal.

The cap assembly 320 may include a cap plate 340, an insulation plate350, a terminal plate 360 and an electrode terminal 330. The capassembly 320 may be associated with a separate insulation case 370, andmay then be coupled to the upper opening 310 a so as to tightly seal thecan 310. The cap plate 340 may have a hole 342 provided therein for theinjection of electrolyte. The cap plate 340 may be formed of a metal andmay have a thickness of about 0.8 mm. The cap plate 340 will bedescribed in greater detail below.

The insulation plate 350 may be made from an insulation material and maybe attached to a lower surface of the cap plate 340. The insulationplate 350 may have a hole 351 formed therethrough corresponding to ahole 341. The electrode terminal 330 may extend through the holes 341,351. The insulation plate 350 may also have a recess 352 formed in alower surface thereof, in order to receive the terminal plate 360.

The terminal plate 360 may be made of a metal, e.g., a nickel alloy, andmay be attached to the lower surface of the insulation plate 350. Theterminal plate 360 may have a hole 361 formed therethrough correspondingto the hole 341, such that the electrode terminal 330 may pass throughthe holes 341, 361. The electrode terminal 330 may make contact with theterminal plate 360, e.g., along a contact region at the periphery of thehole 361. Accordingly, the electrode terminal 330 may pass through theholes 341, 351 and 361, and may be electrically connected with terminalplate 360, while being electrically insulated from the cap plate 340 bya gasket 346 and the insulation plate 350.

The negative electrode tap 317, which is coupled to the negativeelectrode plate 315, may be welded to a side of the terminal plate 360.The positive electrode tap 316, which is coupled to the positiveelectrode plate 313, may be welded to a side of the cap plate 340opposite to the negative electrode tap 317. Alternatively, the negativeelectrode tap 317 may be welded to the cap plate 340, and the positiveelectrode tap 316 may be welded to the terminal plate 360. Suitablewelding methods may include, e.g., resistance welding, laser welding,etc.

The electrode terminal 330 may have the gasket 346 mounted thereon. Thegasket 346 may be made of any suitable insulating material including,e.g., the material used for the insulation plate 350. The gasket 346 maybe any suitable form, including, e.g., tubular, annular, flat with ahole defined therethrough, etc. The electrode terminal 330 may beinserted, along with the gasket 346, into the hole 341, such that theelectrode terminal 330 is insulated from the cap plate 340.

The electrode terminal 330 may be connected to the negative electrodetap 317, and thus to the negative electrode plate 315, or it may beconnected to the positive electrode tap 316, and thus to the positiveelectrode plate 313, so as to operate as a negative or positiveelectrode terminal.

Embodiments of the battery and battery housing, and, in particular, thecap plate 340, will now be described in greater detail with reference toFIGS. 4A-8B. In FIGS. 5A-8B, the cap assembly 320 of FIGS. 4A-4B mayhave the cap plate 340 substituted by cap plates 540, 640, 740 and 840.

FIG. 4A illustrates a plan view of the cap plate 340 for the battery andbattery housing, according to a first embodiment of the presentinvention, and FIG. 4B illustrates a sectional view of the cap plate 340of FIG. 4A, taken along line A-A in FIG. 4A. Referring to FIGS. 3, 4Aand 4B, the battery and battery housing according to the firstembodiment of the present invention may include the cap plate 340. Thecap plate 340 may be, e.g., a metal plate, and may have a shape anddimensions corresponding to the upper opening 310 a of the can 310illustrated in FIG. 3, in order to be installed therein.

The cap plate 340 may have the hole 341 formed therethrough, at a centerportion thereof, the hole 341 having a predetermined size, toaccommodate the insertion of the electrode terminal 330. When theelectrode terminal 330 is inserted into the hole 341, the gasket 346 maybe mounted around the periphery of the electrode terminal 330 andinserted, along with the electrode terminal 330, into the hole 341, inorder to insulate the electrode terminal 330 from the cap plate 340. Thecap plate 340 may also have the hole 342 formed at a side thereof forthe injection of electrolyte.

Referring to FIGS. 4A and 4B, the cap plate 340 may have steppedportions 410 formed therein, the stepped portions 410 configured toextend away from the bulk of the battery housing when the cap assembly320, which includes the cap plate 340, is assembled to the can 310. Thatis, the stepped portions 410 may extend upward, away from the body ofthe battery, and correspondingly define a concave underside of the capplate 340.

Referring to FIGS. 3 and 4B, the stepped portion 410 may be inclined atan angle with respect to a longitudinal axis b of the battery. This mayallow the cap plate 340 to bend outward easily, away from the body ofthe battery, when the lithium secondary battery is subjected to thetransversely-applied force Fa.

The stepped portion 410 may have a height h greater than about 50% ofthe thickness t of the cap plate 340. In other words, the upper surfaceof a center region 445 of the cap plate 340 may be offset from the uppersurface of the peripheral regions of the cap plate 340 by the height h,i.e. offset away from the body of the battery by the height h. Theheight h may be determined in consideration of the final assembly of thecap plate 340 to the other elements of the cap assembly 320. Dependingon the thickness t of the material used for the cap plate 340 and therelative dimensions of the cap assembly 320, the can 310, etc., thestepped portion 410 may have a height h of about 0.1 mm to about 0.5 mmin some implementations.

If the height h of the step portion 410 is too small, e.g., smaller thanabout 0.1 mm, the cap assembly 320 may have little or no effect when thecan 310 is subjected to the transverse force Fa, and the cap assembly320 may not deform away from the body of the battery. If the height h ofthe step portion 410 too great, e.g., larger than about 0.5 mm, the capassembly may be effective at bending away from the body of the batteryin response to the transverse force Fa, but the cap assembly 320 mayhave an overall height that is too great, such that the battery does notsatisfy the size requirements of the particular application. However,where size requirements are not an issue, the height h of the steppedportion 410 need not be limited.

FIG. 5A illustrates a plan view of a cap plate for the battery andbattery housing, according to a second embodiment of the presentinvention, and FIG. 5B illustrates a sectional view of the cap plate ofFIG. 5A, taken along line B-B in FIG. 5A. Referring to FIGS. 5A and 5B,the cap plate 540 according to this embodiment of the present inventionmay include a stepped portion 510 protruding upward, wherein the sidesurfaces are vertically formed. The stepped portion 510 is configured tocause the cap plate 540 to bend outward in response to the transverseforce Fa, so as to reduce the chances of an internal electric shortcircuit, in similar fashion to that described above in connection withthe cap plate 340. However, the vertically formed side surfaces of thestepped portion 510 may cause the cap plate 540 to bend outward to alesser extent than the cap plate 340.

FIG. 6A illustrates a plan view of a cap plate for the battery andbattery housing, according to a third embodiment of the presentinvention, and FIG. 6B illustrates a sectional view of the cap plate ofFIG. 6A, taken along line C-C in FIG. 6A. Referring to FIGS. 6A and 6B,the cap plate 640 according to this embodiment of the present inventionmay include a stepped portion 610 protruding upward, wherein the sidesurfaces are curved. The stepped portion 610 is configured to cause thecap plate 640 to bend outward in response to the transverse force Fa, insimilar fashion to that described above in connection with the cap plate340. However, by forming the stepped portion 610 in the form of a smoothcurve, it may be possible to reduce stresses in the cap plate 640material during manufacture of the cap plate 640 and when the transverseforce Fa is applied to the battery.

FIG. 7A illustrates a plan view of a cap plate for the battery andbattery housing, according to a fourth embodiment of the presentinvention, and FIG. 7B illustrates a sectional view of the cap plate ofFIG. 7A, taken along line D-D in FIG. 7A. Referring to FIGS. 7A and 7B,the cap plate 740 according to this embodiment of the present inventionmay include stepped portions 710 protruding upward, wherein a centerregion 745 of the cap plate 740 is defined by the stepped portions 710.The stepped portions may protrude upward in any suitable form,including, e.g., at an angle, perpendicular to the major plane of thecap plate 740, or in a rounded shape, as described above in connectionwith FIGS. 4A-6B.

The center region 745 may constitute a predetermined portion of the capplate 740. In particular, the length l₁ of the center region 745, asdefined by two stepped portions 710, may be about 20% to about 70% ofthe overall length of the cap plate 740.

If the length l₁ of the center region 745 is greater than about 70% ofthe overall length of the cap plate 740, the center region 745 may betoo long. In particular, the end regions of the cap plate 740, outsidethe center region 745, may be so short that welding in the end regionsbecomes impractical. Furthermore, if the center region 745 is too long,it may have a detrimental effect on the ability of the cap plate 740 todeform outwardly in response to the transverse force Fa. Specifically,the magnitude of the outward deformation of the cap plate 740 may beinsufficient to provide the desired margin of safety for the electrodeassembly 312, i.e., the electrode assembly 312 may get short circuitedwhen the battery housing is deformed.

If the length l₁ of the center region 745 is less than about 20% of theoverall length of the cap plate 740, the center region 745 may be tooshort. In particular, it may make the mounting of a terminal plate 360to the insulation plate 350 unstable when the cap assembly 320 is puttogether.

The stepped portions 710 also define end regions 746 of the cap plate740. Each end region 746 may have a length l₂ of about 1 mm to about 10mm, as defined between the stepped portion 710 and the end of the capplate 740. In an implementation, the cap plate 740 has a thickness of0.8 mm, and the end region 746 has a length l₂ that is greater thanabout 1 mm, in order to provide a stable portion whereby the cap plate740 is welded to the upper opening 310 a of the can 310. The end region746 may also have a length l₂ that is less than or equal to about 10 mm,in order to allow enough room in the center region 745 for theinsulation plate 350 and the terminal plate 360, which are mounted belowthe cap plate 740.

FIG. 8A illustrates a plan view of a cap plate for the battery andbattery housing, according to a fifth embodiment of the presentinvention, and FIG. 8B illustrates a sectional view of the cap plate ofFIG. 8A, taken along line E-E in FIG. 8A. Referring to FIGS. 8A and 8B,the cap plate 840 according to this embodiment of the present inventionmay include a feature 810, wherein the feature 810 is a concave recessformed on the underside of the cap plate 840. The feature 810 isconfigured to cause the cap plate 840 to bend outward in response to thetransverse force Fa, in similar fashion to that described above inconnection with the cap plate 340.

In the cap plate 840, the upper surface of the cap plate 840 may besubstantially planar, while the opposite surface, i.e., the innersurface when the cap plate 840 is installed in the can 310, has thefeature 810 formed therein. The feature 810 may be, e.g., a groove.Whereas the center region of the cap plate is displaced or verticallyoffset from the end regions of the cap plate in the embodimentsdescribed above in connection with FIGS. 4A-7A, in the fifth embodimentthe center region of the cap plate 840 may be substantially coplanarwith the end regions of the cap plate 840.

The feature 810 may be formed as a continuous, substantially rectangularfeature, i.e., a substantially rectangular loop, that defines a centerregion inside the feature 810, as illustrated in FIG. 8A. The feature810 may surround the electrode terminal 830. In another implementation,discontinuous features 810 may be formed, e.g., a pair of linearfeatures (not shown) may be formed across the width of the cap plate840, i.e., so as to be transverse to the line E-E in FIG. 8A. Stillother implementations are possible, including continuous featuresdefining, e.g., a rectangle having equal length sides (a square), anellipse, etc.

The feature 810 may be formed by any suitable operation including, e.g.,etching or stamping. In an implementation, the feature 810 is formed bya stamping operation. As described above, the upper surface of the capplate 840 may be substantially planar. However, where the feature 810 isformed by stamping, the stamping operation may generate a correspondingconvex protuberance 810′ extending above the substantially planarsurface of the cap plate 840, away from the battery. That is, in theimplementation illustrated in FIGS. 8A and 8B, a stamping operation maysimultaneously form the feature 810 on the underside of the cap plate840 and the corresponding protuberance 810′ on the top side of the capplate 840. Thus, the protuberance 810′ may be a relatively narrowelevated feature formed in a substantially rectangular loop shape. Apartfrom this protuberance 810′, the upper surface of the cap plate 840 maybe planar.

Hereinafter, the operation of the battery and battery housing accordingthe present invention will be described. FIG. 9 illustrates ageneralized perspective view of a compressed battery housing accordingto the present invention. Referring to FIG. 9, when the battery isdeformed by the transversely-applied force Fa so as to compress thesides inward, i.e., in a direction normal to the longitudinal axis b,the substantially flat bottom surface of the can 110 may deform inwardand upward. However, the cap assembly may be bent upward and outward. Asa result, no force is applied to the upper portion of the electrodeassembly contained in the battery housing, so that an internal electricshort circuit does not occur in the electrode assembly.

In other words, if the stepped portion or recessed feature is formed asdescribed above in connection with FIGS. 4A-FIG. 8A, pressure applied tothe electrode assembly can be minimized in the safety compression test,wherein a prescribed force is applied to the sides of the battery,thereby improving the safety of the battery.

Exemplary embodiments of the present invention have been disclosedherein, and although specific terms are employed, they are used and areto be interpreted in a generic and descriptive sense only and not forpurpose of limitation. For example, while the battery housing isdescribed as having the cap plate separately provided and mounted to thebattery housing, it will be appreciated that the cap plate according tothe present invention may be monolithically formed with the batteryhousing, e.g., by a deep drawing process, and another portion of thehousing, e.g., a separately formed bottom plate, may be separatelyprovided in order to allow installation of the electrode assembly.Moreover, it will be appreciated that the present invention, whiledescribed above in the context of a prismatic or rectangular battery,may similarly be applied to cylindrical batteries, e.g., cylindricallithium secondary batteries.

Accordingly, it will be understood by those of ordinary skill in the artthat various changes in form and details may be made without departingfrom the spirit and scope of the present invention as set forth in thefollowing claims.

What is claimed is:
 1. A prismatic battery, comprising: an electrodeassembly including electrode plates and a separator; a can defining aspace receiving the electrode assembly; and a cap plate covering thespace, the cap plate being configured to deform away from the space whenpredetermined sides of the can are deformed toward the space, wherein ahole is defined through the cap plate in a center region thereof,wherein the electrode assembly further includes an electrode terminaldisposed through the hole such that an upper portion thereof is exposedat an exterior of the prismatic battery, the electrode terminal beingelectrically coupled to one of the electrode plates via a terminal plateand being electrically insulated from the cap plate, wherein the capplate has at least two stepped portions extending away from the space,the at least two stepped portions: forming one concave feature aroundthe center region including a center portion on which the hole isformed, and offsetting the center region from peripheral regions of thecap plate such that a distance from the center region to the space isgreater than a distance from the peripheral regions to the space,wherein each stepped portion has a side surface inclined at an anglewith respect to a major surface of the cap plate, and wherein theterminal plate and the electrode terminal are coupled to the cap plate,the terminal plate and a lower portion of the electrode terminal beingdisposed between the concave feature and the electrode assembly.
 2. Theprismatic battery as claimed in claim 1, wherein the concave feature hasa long dimension with a length of 20% to 70% of the cap plate.
 3. Theprismatic battery as claimed in claim 2, wherein each stepped portionhas a height equal to at least 50% of a thickness of the cap plate. 4.The battery as claimed in claim 2, wherein the at least two steppedportions extend away from the space, the stepped portions defining thecenter region of the cap plate.
 5. A prismatic battery, comprising: anelectrode assembly including electrode plates and a separator; a candefining a space receiving the electrode assembly; and a cap platecovering the space, the cap plate being configured to deform away fromthe space when predetermined sides of the can are deformed toward thespace; wherein a hole is defined through the cap plate in a centerregion thereof, wherein the electrode assembly further includes anelectrode terminal disposed through the hole such that an upper portionthereof is exposed at an exterior of the prismatic battery, theelectrode terminal being electrically coupled to one of the electrodeplates via a terminal plate and being electrically insulated from thecap plate, wherein the cap plate has grooves, each of which being formedon an inner surface of the cap plate between end regions of the capplate and the center region of the cap plate and facing the space suchthat the grooves have a concavity open towards the space, wherein theinner surface of the cap plate at the end regions is coplanar with theinner surface of the cap plate at the center region, and wherein theterminal plate and the electrode terminal are coupled to the cap plate,the terminal plate and a lower portion of the electrode terminal beingdisposed in a region between the grooves.
 6. The prismatic battery asclaimed in claim 5, wherein the grooves are continuously formed in loopshape and enclose the center region.
 7. The prismatic battery as claimedin claim 6, wherein the loop-shaped grooves enclose a rectangularregion.
 8. The prismatic battery as claimed in claim 5, wherein at leasttwo grooves are extended laterally across a width of the cap plate.
 9. Abattery housing of a prismatic battery for housing a battery electrodeassembly, the battery housing comprising: a body, the body defining aspace to contain the battery electrode assembly and the batteryelectrode assembly including electrode plates and a separator; and a capplate defining an upper wall of the space, the cap plate beingconfigured to deform away from the space when predetermined sides of thebody are deformed toward the space, and the cap plate having at leasttwo stepped portions extending away from the space, the at least twostepped portions: forming one concave feature around a center regionincluding a center portion on which a hole is formed, and offsetting thecenter region from peripheral regions of the cap plate such that adistance from the center region to the space is greater than a distancefrom peripheral regions to the space, wherein each stepped portion has aside surface inclined at an angle with respect to a major surface of thecap plate, wherein the hole is defined through the concave feature ofthe cap plate in the center region of the cap plate, wherein theelectrode assembly further includes an electrode terminal disposedthrough the hole such that an upper portion thereof is exposed at anexterior of the prismatic battery, the electrode terminal beingelectrically coupled to one of the electrode plates by a terminal plateand being electrically insulated from the cap plate, and wherein theterminal plate and the electrode terminal are coupled to the cap plate,the terminal plate and a lower portion of the electrode terminal beingdisposed between the concave feature and the electrode assembly.
 10. Thebattery housing as claimed in claim 9, wherein the body and the capplate are monolithically formed.
 11. The battery housing as claimed inclaim 9, wherein the at least two stepped portions extend away from thespace and laterally across a width of the cap plate, the at least twostepped portions defining the peripheral regions and the center regionsuch that an inner surface of the center region is not coplanar withinner surfaces of the peripheral regions.
 12. A battery housing of aprismatic battery for housing a battery electrode assembly, the batteryhousing comprising: a body, the body defining a space to contain thebattery electrode assembly and the battery electrode assembly includingelectrode plates and a separator; and a cap plate defining an upper wallof the space, wherein the cap plate is configured to deform away fromthe space when predetermined sides of the body are deformed toward thespace, wherein an inner surface of end regions of the cap plate iscoplanar with an inner surface of a center region of the cap plate,wherein a hole is defined through the cap plate in the center region,wherein the electrode assembly further includes an electrode terminaldisposed through the hole such that an upper portion thereof is exposedat an exterior of the prismatic battery, the electrode terminal beingelectrically coupled to one of the electrode plates by a terminal plateand being electrically insulated from the cap plate, wherein the capplate has grooves, each of which being formed on the inner surface ofthe cap plate between the end regions of the cap plate and the centerregion of the cap plate and facing the space such that the grooves havea concavity open towards the space, and wherein the terminal plate andthe electrode terminal are coupled to the cap plate, the terminal plateand a lower portion of the electrode terminal being disposed on a regionbetween the grooves.
 13. The battery housing as claimed in claim 12,wherein the grooves are continuously formed in a loop shape.
 14. Thebattery housing as claimed in claim 13, wherein the loop-shaped groovesenclose a rectangular region.